Tourism is a major industry along the Lake Michigan shoreline of Indiana, but in recent years it has been necessary to intermittently close public bathing beaches, as a result of high levels of E. coli contamination in nearshore waters. In order to understand, predict, and ultimately prevent such contamination, the role of bacterial flushing from land-based sources must be better understood.

Objective:

This project characterized temporal variations in bacterial outfalls at the mouths of creeks (such as Burns Ditch) that flow into Lake Michigan.

Approach:

We continuously monitored flow and water quality at the outlet of Burns Ditch, collected water samples for bacterial analysis during three storm periods and one dry period, and developed statistical relationships between water-quality parameters (for example, pH, dissolved oxygen, temperature, and turbidity) and bacterial concentrations in stream flow. The statistical equations were used to characterize bacterial outfalls when samples were not being collected.
During 1998-1999, instruments were installed and continuous monitoring was conducted. Samplings for bacterial contamination were conducted over 24-hour periods during two storms.

Products:

The project Web page on the Indiana Geological Survey's Web site summarizes the results of the study: http://igs.indiana.edu/survey/projects/burns_web/index.cfm

Benefits:

Statistical correlations between E. coli outfalls and related water-quality parameters constitutes a significant component in an early warning system for beach closures along the southern shore of Lake Michigan.